The relationship of the alpha-2-globulin fraction (conformation and effect on tryptophan uptake) to schizophrenia will be studied. Various groups of individuals, comprising chronic hospitalized schizophrenia patients, acute schizophrenia patients, hospitalized non-schizophrenia patients, depressed patients, patients with other diseases, families of mentally ill patients and control families will be studied. A chicken erythrocyte system will be used to measure tryptophan uptake. Human erythrocytes will also be investigated in this connection.